EDIT: Herpa derp derp. While I suggest reading the stuff below, I completely blanked on the fact that there is a seminar devoted to players who primarily use DSX. It’s called “Antigravity”.
In terms of the actual mechanics of making the picking hand work for downstroke escape, as far as I can see, the Pickslanting Primer is the best resource.
As previous posters mentioned, the Strunz and Farah interview and any of the stuff with Andy Wood includes lots of DSX. Frank Gambale mixes DSX and USX, and there’s lots of good DSX in the Gambale stuff.
That said, once you understand how single-escape works with USX, you can apply the underlying principles to DSX.
As far as I’ve seen, the most systematic presentations of how to “make licks work” for single-escape picking in general are the “Volcano Seminar” (deconstructing Yngwie) and the “Cascase Seminar” (deconstructing Eric Johnson).
While those players and the presented material are USX, the same conceptual framework for integrating the left and right hand can also be applied to DSX. The over-arching theme is that while Eric and Yngwie don’t preach “systems”, they each “discovered” their way into fast licks that follow a single-escaped system. With an understanding of that single-escaped system, you can design an effective approach for single-escaped licks in general.
The main limitation that arises when trying to re-arrange “USX” licks to be playable as “DSX” is for licks that include sweeps, or “mini-sweeps” a.k.a. “directional picking” or “economy picking” (i.e. USX with consecutive downstrokes to change to the adjacent higher-pitched string, versus DSX with consecutive upstrokes to change to the adjacent lower-pitched string). You can always be like Gambale and learn to mix-and-match those approaches, changing your escape direction as needed, but it’s an important idea to grasp for understanding the limits of trying to translate USX repertoire to DSX (or vice versa). But in general, the limitation only arises in situations where a lick includes a single note on a string followed immediately by a string change: your choice of USX or DSX determines the direction your “trapped” pick can pick the adjacent string without hopping.